Well tools for subsurface flow control



Aug. Z8, 1962 N. K. ANDREW ETAL 3,051,245

WELL TooLs FOR SUBSURFACE FLow CONTROL Filed Aug. 19, 1958 s sheets-sheet 1 rfi M' QM g /Vormah ANO/few blz/yb E. Mefca/f I INVENTORS 1f- Z 4MM f@ @Tron/Vey Allg- 28, 1962 N. K. ANDREW ETAL 3,051,245

WELL TOOLs FOR suBsURFAcE FLOW CONTROL Filed Aug. 19, 1958 3 Sheets-Sheet 2 /VO/man ff. nd/'ew Hu f. Me zca/f INVENTORS ATTORNEY Aug. 28, 1962 N. K. ANDREW ETAL 3,051,245

WELL TOOLS FOR SUBSURFCE FLOW CONTROL Norma/7 f, Hug E. Mecq/f- INVENTORS Bzw@ A/m A from/5y tra irre' 3,051,245 WELL TOOLS FOR SUBSURFACE FLOW CNTROL Norman K. Andrew and Hugh E. Metcalf, Houston, Tex., assignors to Johnston Testers, Inc., Sugar Land, Tex., a corporation of Texas Filed Aug. 19, 1958, Ser. No. 755,932 15 Claims. (Cl. 166-226) This invention relates to well tools and, more particularly, lto tools for connection with well pipe to provide subsurface control of fluid flow such as may be required in formation testing.

Formation testing tools employed to admit and retain iiuid samples have evolved over a period of years from a type utilizing Ia heavy spring to keep the test ports closed to a type having an hydraulically delaped opening. Representative of the spring-type are the formation testing tools of Johnston Patents Nos. 1,790,424 and 2,073,107, while tools of the hydraulic type are disclosed in Deters et al. Patent No. 2,703,696 and Moosman Patent No. 2,737,246. Tools of the spring-type enjoyed a widespread use characterized -by eicient and economical operation and only in recent' years have been replaced by the highly versatile and reliable hydraulic testing tools.

in a typical assembly of a spring-type testing tool, such as that disclosed in Patent No. 2,073,107, it was common practice to include a so-called trip valve spaced above the testing tool. Should the test ports for any reason open prematurely during descent, as when a constriction or bridge in the well was encountered, such trip valve ensured that well fluid would not enter the drill string thereabove. With the introduction of the hydraulic-type testing tool, the hydraulically delayed opening of the test ports prevented premature entry of fluid and removed the need for a trip lvalve. The transition from spring-type to hydraulic-type tools was also accompanied by a change from a poppet valve With a metal-to-metal seal to a sliding valve with a resilient seal.

Despite the many advantages in the hydraulic testing tools which have -thus evolved, there has remained in the iield a desire to return to the operating economy and positive action characterizing the spring-type ltool.

It is therefore, an object of the present invention to provide an improved formation testing tool adapted for positive and economical operation.

It is also an object of the present invention to provide an improved well tool which is characterized by -a highly reliable seal in the closed position.

Another object of the present invention is to provide a well tool which incorporates a valve having a positive opening characteristic with a minimum likelihood of premature opening.

A further object of the present invention is to provide a new and improved Well tool having substantially an optimum suitability for admitting and retaining samples of formation fluid in the testing of well formations under widely varying and adverse conditions.

Yet another object of the present invention is to provide a well tool which may readily be operated and maintained by iield personnel.

These and other objects `of the invention are obtained by providing an annular valve disposed between a tubular housing and a mandrel slidably -received in the housing. Such valve includes a seat formed within the bore of the housing and an annular valve head movable with respect to both the housing and -the mandrel and displaced relative to the valve seat after a predetermined stroke of the mandrel. More particularly, the annular valve head is slidably disposed along a flow channel defined by the mandrel and the housing for opening and closing movement in the manner of a poppet valve. When hydrostatic pressure .is overcome in the initial opening ofthe annular valve, a detectible impulse is obtained at the surface. A secondary valve is incorporated in the Itool for a more reliable seal upon reclosing of the tool.

In one embodiment of the invention, a sliding seal is maintained along the channel between Vthe mandrel and the housing to provide a `secondary valve which remains closed prior to the accomplishment of the predetermined stroke by which the mandrel opens the annular valve. When the annular valve head is displaced Ifrom its closed position by stroking of the mandrel, the sliding seal is received protectively by the valve head to avoid its erosion by iluid passing through the annular valve. VA onepiece liner section cooperates with the sliding seal'and the valve head to provide sealing surfaces which may readily be replaced. In another embodiment, a twoiece liner section is employed.

In yet another embodiment, two annular valve heads are spaced along the flow channel to provide sequentially opened metal-to-metal or poppet valves. In addition, a third -annular valve head may be employed to open and Aclose equalizing ports with stroking of the mandrel rela-- tive to the housing.

Additional objects and advantages of the invention will become apparent from the following detailed description of representative embodiments thereof, taken in conjunc-A `tion with the accompanying drawings, in which:

FIG. 1 is a view -in elevation of a well tool in accordance with the present invent-ion assembled in a string of pipe arranged for formation testing; l

FIG. 2 is a detailed vertical vsection of valve portions of the well tool taken along the lines 2--2 of FIG. 1i

FIG. 3 is a view similar to FIG. 2 showing the well tool in open `opsition -for receiving a formation uid sample; A

FIG. 4 is a -view similar to FIG. 2 showing the well tool in its intermediate closed or shut-in position for obtaining a shut-in pressure test;

FIGS. 5A and 5B are detailed vertical sections of a modified well tool in closed position showing, respectively, the hydraulic delay and valve portions of the well tool; and t FIGS. 6, 7 Iand 8 are detailed vertical 4sections of modified valve portions of the well tool of FIGS. 5A land 5B, showing the same in closed, intermediate-and open positions.

In FIG. 1 is `shown a well tool 10- exemplifying vthe principles of the present invention and including a valve portion 11 at its lower end which is described in detail hereafter in connection with FIGS. 2-4. At its upper end end is ya control portion `12 which may of the type shown and described in copending application Serial No. 495 ,247-r iiled by Benjamin P. Nutter on March 18, 1955, now Patent No. 2,901,001, for Hydraulic Tester and Shut- In Pressure Too i Q The well tool 10 is arranged to be dependently secured to a string 14 of drill pipe or tubing for lowering through a borehole 15 to a desired depth. The borehole 15 may be cased or uncased and, when uncased as illustrated, such depth is generally selected to provide a good seatv for a packer 16 dependently secured to the well tool 10 and supported off the bottom of the borehole by-anchor means, such as perforated anchor pipe 17. For example, the anchor pipe 17 may be of such length as to position the packer 16 against the wall of a hard formation 18-Av just above a permeable formation 19 which is toy be tested for fluid production. The anchor pipe 17 mayv provide a housing for one orl more pressure recorders (not shown) which may be ofthe type described in M. A. Garrison Patent No. 2,816,440.

Referring to FIGS. 1 and 2, the well tool 10 in accordance with the present invention includes a multi-section tubular housing 20'made up of sections 21, 22, 23, 2A- .and 25 threadedly connected together in end-to-end duid-tight alignment. Slidably but nonrotatably receivedl within the housing 2 0 for movement between an extended and retracted position is a tubular mandrel 26 which may likewise be of sectional construction including sections 27, 28, 30, 31 and 32, threadedly connected together in end-to-end duid-tight alignment. Such nonrotation may result lfrom the interiitting of splines (not shown) carried bythe housing section 21 and themandrel section 28, for example.

The mandrel 26 is connected in fluid-tight relation to the pipe string 14 above by means of a top tubular sub 34 having a standard threaded connection with the string 14 and a threaded driving connection 35 with the upper mandrel section 27. The drive connection may, for example, be provided by an Acme thread such that rotation of the top sub 34 by rotation of the pipe string 14 (conventionally to the right) draws the mandrel section 27 upwardly into the top sub. At the same time, the threaded driving connection 35 serves to transmit longitudinal movement of the top sub 34 to the mandrel 26. In order that a longitudinal uid channel 70 provided by the bore of the mandrel 26 may be continued upwardly in sealed relation past the drive connection 35 into ow course 71 defined by the bore of the pipe string 14, -a wash pipe 37 has a fluid-tight threaded connection with the upper mandrel section 27 and extends upwardly through an internal shoulder 39 in the top sub 34 in scaled sliding relation thereto.

As thus far described, the control portion 12 of the well tool provides for downward stroking of the mandrel 26 relative to the housing 20 by a downward movement of the pipe string 14 transmitted through top sub 34 and threaded drive connection 35. Downward travel of the mandrel is limited by engagement of the lower end of top sub 34 with the upper end of housing section 21 and a thrust bearing 46 may be positioned therebetween t0 facilitatel rotation of the top sub 34 relative to the housing section 21 under load conditions. When the top sub 34 is rotated by the pipe string 14, the mandrel 26 is displaced upwardly by threading of the mandrel section 27 into the top sub 34. This upward displacement may, for example, be approximately half the previously described downstroke. Upon upward movement of the pipe string 14 and top sub 34 relative to the housing 20, the mandrel 26 is returned to its original upper position, the limit of its travel being determined by the interengagement of mandrel section 27 and housing section 21,l forl example. Thus, the mandrel may be placed at iirst, second and third positions (as shown in FIGS. 2, 3 and 4, respectively) by the remote manipulations of the pipe string 14,'or as described in more detail in the aforementioned application Serial No. 495,247. As further taught in that application, the top sub 34 may dependently support a sleeve 43 which serves to co-rotatively secure the top sub to the housing section 21 in the first or upper position of the mandrel while permitting rotation of -the top sub relative to the housing section for movement of the mandrel between its second (or lower) and third (or intermediate) positions.

'KTo retard downward movement of the mandrel relative to the housing, housing section 22 incorporates an annular hydraulic fluid chamber 52 (FIG. 2)' through which the mandrel 26 extends. A variety of arrangements may be employed for retarding the stroke of the mandrel through this hydraulic fluid chamber, exemplary arrangements being described in the aforementioned application'Serial No. 495,247 and hereafter in conjunction with FIG. 5A. While the downstroke of the mandrel is thus retarded for a time-delayed travel, provision is made for an unrestricted upstroke. f

Turning now to a detailed consideration of valve portion 11 of the well tool, reference is made to FIG. 2.

The annular chamber 52 is shown to be sealed off at its bottom end by means of `an annular O-ring retainer 53 including O-rings 57 affording a sliding seal with the mandrel section 30 and O-ring 58 sealed with the housing, the retainer 53 being secured with respect to the housing 20. A liner section 74 extends upwardly into the housing section 23 and is secured to the same by means of a thread connection 75. An enlarged portion 76 of the liner section 74 extends below the housing section 23 into an enlarged bore 78 defined -rby the housing section 24. Por easy maintenance, the enlarged portion 76 of the liner section affords an external surface 79 which is exposed to receive a wrench when housing section 24 is unthreaded from housing section 23 so that the thread connection 75 may readily be made or broken. The enlarged portion 79 also defines an upwardly directed shoulder Si) which abuts against the lower end face of housing section 23 for transmission of compression loads. To prevent leakage of fluid externally of the liner section 74 past the shoulder Si! and thread connection 75, an O-ring 81 may be received in an external groove formed in the liner section 74 to seal with the bore of housing section 23.

Within the enlarged bore 78 defined by the housing section 24 is an annular valve head 82 having a valve surface 83 at its upper end confronting a valve seat 84 formed' on the lower end face of the liner section 74. The valve head 82 and seat 84 together deiine an annular valve serving to control the ilow of uid through the ow channel 70 defined by the mandrel and housing and extending lengthwise through the entire well tool. Since the well fluid or connate iluid which is admitted through the flow channel 70 into the pipe string 14 is often of an abrasive character and frequently iiows at high velocity, the liner section 74 and the valve head 82 and valve seat 84 are preferably constructed of a tough, erosion resistant material such as a suitable steel to provide la metalto-metal seal. The sealing action is enhanced by the configuration of the valve seat 84 tending to center the sealing face 83 of the valve head 82 in conforming, fitted relation. Also, the conliguration follows the line of fluid iiow. Thus, the valve seat 84 is preferably formed with a conical taper opening downwardly and having an inl clination with respect to the axis of the well tool such as 45 and lying within the angular range of greater than a sticking taper (on the order of 7) but less than a flat the valve head face 83 having a complemenary taper.

To provide for ample ilow of uid externally past the valve head 82 when it is displaced downwardly to an open position, the exterior diameter of the valve head is substantially less than the interior diameter of the enlarged housing bore 78. By providing the valve head 82 with a bore 86 `sized to slidably receive the lower section 32 of the mandrel and by retaining the O-ring 87 within an internal groove relieved from the bore 86 for a sliding seal with the uniform exterior of the mandrel section 32, leakage of uid between the mandrel and valve head 82 is precluded. The valve head 82 is further provided with a counter bore S9 opening upwardly for ya purpose to be explained hereafter.

When submerged in well fluid, the valve head 82 is arranged -to be maintained in its sealed or closed position by hydrostatic pressure. Thus in the assembly of the well tool 10 in a well string for purposes of formation testing, for example, as illustrated in FIG. l, well fluid 1s admitted through the perforation of anchor pipe 17 and flows upwardly through the packer 16 into the bottom section of the well tool housing. The lengthwise liow channel 70 through the well tool extends upwardly from the bore of the bottom housing section 25, through a longitudinal bypass passage 90 formed in a reduced bore portion 92 of housing section 24 and into the enlarged bore 7S of the housing section 24. The upward hydrostatic force applied against the valve head 82 is then i proportional to the product of the hydrostatic pressure at the given depth and the annular area, the inner diameter of which corresponds with the outer diameter of the mandrel section 32 inwardly of the O-ring 87 and the outer diameter of which corresponds with the effective diameter -of the seal between the valve head face 83 and the valve seat 84. For a pressure of, say, 10,000 p.s.i. the valve head 82 may be designed to experience a seating force in its closed position on the order of 6,000 pounds.

However, since the well tool is generally introduced into a well in `a dry condition, it is desirable that the valve head 82 be retained in its upper, closed position against the force of gravity by a biasing force in addition to the frictional force developed by the O-ring 87. Such biasing force is conveniently developed by a coil spring 94 developing a force in compression of, say, 100 lbs. or higher. While the lower end of the coil spring 94 may be supported with respect to the mandrel, preferably it bears against an upwardly facing annular shoulder 95 formed at the junction of the enlarged bore 78 and the reduced bore section 92, the upper end of the coil spring 94 bearing against the downwardly directed confronting shoulder 96 defined by the lower face of the valve head 82. The mandrel section 32 thus extends through not only the valve head 82 but also the coil spring 94 to support the same in alignment.

To prevent an upward flow of fluid through the bore of the mandrel section 32 which would bypass the annular valve 82-3384, there is retained at the threaded connection between mandrel sections 31 and 32 a downwardly opening check valve 98 which may be opened by uids pumped downwardly through the pipe string 14 under pressure for emergency purposes but is otherwise closed to retain any fluids standing in the bore of the mandrel thereabove. Reference may be had to the aforementioned application Serial No. 495,247 for a more detailed description of this check valve 98. The ow course 70 extending lengthwise through the well tool thus serves exclusively for the upward flow of fluids through the well tool and into the pipe string 14.

Above the valve head 82 the flow course 70 is defined by Ithe annular region between the uniform bore 100 of the liner section 74 and the external surface 88 of the mandrel section 32. In the closed position of the well tool illustrated in FIG. 2, the flow course 70 is sealed off not only by the valve head 82 but also by a sliding seal 102 effected between the mandrel and the liner bore 100 and deiining a secondary valve. This seal 102 is provided by a seal ring 103 carried on the mandrel section 31 and longitudinally retained between a downwardly facing annular shoulder 104 of the mandrel section 31 and the confronting upper end 105 of the mandrel section 32.

The seal ring 103 carries an annular packing element 106 which may be in the form of one or more O-rings but, as illustrated, is preferably formed as a band of rubber or other resilient material bonded or otherwise securely retained in an annular groove circumscribing the seal ring 103. To prevent a leakage of fluid between the seal ring -3 and the underlying surface of the mandrel section 31, the seal ring 103 may have an annular groove relieved from its bore to receive an O-ring 107 in sealing contact with the mandrel section.

Thus, the valve head 82 and the seal ring 103 serve to close otf the i'low course 70 by seals of substantially different character, both of which are effective in the closed position of the tool. While the valve head S2 (primary valve) provides the initial seal against fluid pressure applied upwardly through the tool (as occurs, for example, when well tool 10 is being lowered through the well uid 13), lthe seal ring 103 (secondary valve) provides the initial seal against pressure acting downwardly through the tool arising, for example, from the column of recovered fluids retained in the mandrel and pipe string above the seal ring 103 as the well tool is withdrawn.

To complete the flow course 70 through the well tool when ythe valve head 82 and the seal ring 103 are displaced to their open position, the mandrel section 31 is provided with a plurality of ports opening laterally from the bore of the mandrel section to its exterior. Such ports 110 may be directed outwardly and downwardly at an inclination with respect to the axis of the tool, the angle of 45 being exemplary, in order to minimize the eroding eiect of fluids llowing often at high velocities through the tool into the well string. Since the ports 110 are in the section 31 of the mandrel which, in operation remains substantially free of stress and since the ports are not required to pass through any packing, they may be as large in diameter as desired, for example, on the order of one-half the diameter of the mandrel bore and four of them may be employed at right angles to one another.

As may best be seen in FIG. 3, downward stroking of the mandrel relative to the housing brings the seal ring 103 past the valve seat 84 into the counter bore 89 of the valve head 82. Thus, the counter bore 89 is sized with a diameter at least as great as the diameter of the liner bore 100 so as to accommodate the sealing element 106 in the radial direction. The depth of the counter bore 89 to its upwardly directed annular shoulder 112 corresponds with the longitudinal dimension of the seal ring 103 measured between its downwardly directed annular shoulder 113 (which extends outwardly beyond the proiile of the mandrel section 32) and ya point above the sealing element 106. To minimize erosive wear, the upper exterior edge of the seal ring 103 may have a chamfer 115 so as to be sloped in the direction of the test ports 110 and of the valve surfaces 83, 84 defining the direction of ow.

In the manner disclosed in the aforementioned Moosman Patent No. 2,737,246 issued March 6, 1956, for Hydraulic Valve Device, the well tool of the present invention may incorporate equalizing ports 117 in the lower section 32 of the mandrel which, in one position of the mandrel relative to the housing, are in register with lateral ports 118 extending through the wall of the reduced bore portion 92 for the housing section 24. To vfacilitate such registry, the portion 92 of the housing section 24 may have an annular recess 119 relieved from its bore at the inner end of the port 118 and extending above and below it a distance short of the annular packing provided by an upper O-ring 120 and lower spaced O-rings 121-123, these O-rings being received in corresponding grooves relieved from the reduced bore of the housing section 24. The O-rings 120-123 are thus arranged to effect an annular seal between the mandrel section 32 and the housing section 24 above and below the recess 119 and to seal on the port 118 when the' equalizing port 117 of the mandrel is stroked below the O-ring 121.

In an exemplary operation of the well tool 10 as shown in FIGS. l4, the assembled tool is made up in-dependent relation to the string of pipe 14 by threadedly connecting the top sub 34 of the tool to a stand of the pipe. The lower housing section 25 is threadedly connected with the packer 16, and the anchor pipe is connected below the packer. When properly made up,V each thread joint is iiuid tight whereby a continuous flow course is provided upwardly from the perforations of the anchor pipe 17 interiorly through the packer 16, through the flow channel 70 of the well tool 10 and thence upwardly through the pipe string 14 as indicated at 71 ('FIG. l).

While the string is being lowered into a well, this ow course is closed olf by the closure of the valve head 82 upon the valve seat 83 and the further seal effected by the seal ring 103 with respect -to the liner bore 100. However, well fluid may ow upwardly through the anchor pipe perforations and the interior of the packer 16 and outwardly through the equalizing ports 117 and side ports 118 to accommodate a rapid descent of the pipe string despite a relatively close it between the periphery of the packer 16 and the borehole wall. During the descent of the tool into the well, the regis-try of ports 117 and 118 is maintained by the engagement between the mandrel section 28 and the housing section 21 which limits further extension of the mandrel upwardly with respect to the housing. The tendency of the mandrel to move in the direction of such extension relative to the housing is promoted not only by the force of gravity acting downwardly on the housing and the packer and anchor suspended therebeneath but also, if desired, by the hydrostatic unbalance arising from the difference in the sealed outside diameters of the mandrel sections 30 and 32. Thus, by making the mandrel section 32 of a larger diameter at the O-ring 87 than is the mandrel section 30 at the O-rings 57, a net annular area of the housing is effectively exposed to hydrostatic pressure acting downwardly to maintain the housing downwardly displaced to i-ts limit position with respect to the mandrel.

When the anchor pipe 17 engages the bottom of the well, a portion of the weight of the string of pipe may be set upon packer 16 tending to expand the same into sealed engagement with the surrounding formation 18. As the packer is set, formation 19 opposite the anchor pipe 17 is placed in isolated communication through the perforations of the anchor pipe with the flow course extending upwardly through the string. Simultaneously with setting of the packer 16, the weight of pipe applied to the mandrel 26 via top sub 34 causes the mandrel to stroke downwardly with respect to the housing toward its retracted position. The rate of stroking is, however, retarded by ythe hydraulic delaying mechanism within the housing section 22, In dependence upon the desired adjustment of such delaying mechanism, a period of, say, one to lseveral minutes may elapse as the mandrel moves from its closed position illustrated in FIG. 2 to its open position illustrated in FIG. 3.

Such delay allows the well Itool to be spudded or forced by intermittent application of weight through bridges or constrictions encountered as i-t is lowered into the borehole without risk of premature opening of the Valve head 82. It may be observed that the oating support of the valve head whereby it is free for relative longitudinal movement with respect torboth the housing and the mandrel allows the valve head to remain in its closed position despite sudden movements or shocks of the mandrel 26 in the downward direction. For example, when a bridge or constriction in the borehole is suddenly encountered or when the pipe string being lowered into the borehole is suddenly braked, the consequent jugging or shock displacement of the mandrel relative to the housing does not result in opening of the valve head 82. The mass of the valve head 82 is sufliciently slight with respect to the forces tending to hold it in its closed position that inertial forces imposed upon the valve head 82 will not open it.

With downward stroking of the mandrel relative to the housing, equalizing ports 117 -will first be closed by displacement below the O-ring 121. Then, after the elapse of the desired period prior to opening of the tool to a recovery of test fluid, shoulder 113 of seal ring 103 engages shoulder 112 of valve head S2 with the `sealing element 106 protectively received in the counter bore 89. When the mandrel has been stroked downwardly to this point, then, only the seal effected between the Valve head 82 and seat 83 is effective to exclude well fluid from flowing upwardly into the test ports 110 and the well string thereabove.

While the coil spring 94 -tends to resist opening of the valve head 82 by further downward stroking of the seal ring 103 with the mandrel, its force may be of a moderate amount compared with the hydrostatic force arising from pressure unbalance across the valve head, as previously described. In such instance, a very considerable force measured inthe thousands of pounds arises as the seal ring shoulder 113 strikes the valve head shoulder 112 to resist further downward movement of the mandrel. Even with a so-called water cushion comprising a column of water deliberately introduced in the pipe string 14 and standing above the valve head 82, there will remain a substantial hydrostatic pressure difference across the valve head 82 suiicien-t to impose a strong resisting force at the moment of opening the valve head. This suddenly arising force, in any event, creates a shock wave which travels upwardly the length of the pipe string so as to be det-ectible by an operator at the surface to provide an indication of opening of the well tool for flow of fluid into the pipe string. In addition to this significant feature, the hydrostatic unbalance across the valve head 82 also promotes a liuid tight seal across the valve seat 84. Furthermore, a generous annular area for ilow exists when valve head 82 is just off seat 84 whereby erosion at the instant of opening or closing is minimized. It is noteworthy that these advantages are secured while the hydraulic delaying mechanism is still effective to ensure against premature opening.

When the mandrel 26 ha-s completed its downward stroke relative to the housing 20, as determined by endwise engagement between the top sub 34 and the housing section 21 -via bearing `46, the valve head will be in the position shown in FIG. 3 with the test ports 110 fully exposed to accommodate iiow of fluids through the longitudinal passage '70 defined by the mandrel and housing.

After a suicient time has elapsed with the valve head 82 in its open position as illustrated in FIG. 3 to obtain the desired test of the isolated formation, the valve head 82 may be returned to its closed position by an upstroking of the mandrel 26 relative to the housing either to the position shown in FIG. 4 or to the position shown in FIG. 2 depending upon whether or not a so-called shutin pressure test is desired. If such a test is not desired, the valve head 82 may be closed as shown in FIG. 2 simply by picking up weight on the pipe string 14 toy stroke the mandrel upwardly with respect to the housing. The construction of the hydraulic delaying mechanism permits such upstroke to be of unrestricted speed so that the well tool may quickly be closed whenever desired.

When a shut-in pressure test is desired, on -the other hand, the pipe string 14 is rotated, usually to the right, to draw the mandrel 26 upwardly relatively to housing 20 by the operation of thread connection 35 between the top sub 34 and the upper mandrel section 27. As the pipe string is rotated, iirst the valve head 82 seals with respect to the valve seat 84 and then seal ring 103 moves upwardly out of the counter bore 89 and into the bore 100 of lthe liner 74 to seal therewith stopping at the intermediate position illustrated in FIG. 4.

As seen in FIG. 4, rotation of the pipe string 14 strokes the mandrel upwardly a distance. less than that required to bring the equalizing ports 117 into registry with the side ports 118. Hence, upward flow of uid into the well tool and through either the test ports or the equalizing ports 117 is completely shut off and, consequently, the pressure of such iiuid will gradually increase from the flowing pressure toward a static pressure corresponding with the pressure of connate fluid in the isolated formation. Such pressure buildup may be recorded by the pressure recorder (not shown) contained within the `anchor pipe 17. After completion of the shut-in pressure test, the pipe string 14 may be picked up to move the mandrel to its fully extended position corre sponding to that shown in FIG. 2.

When the well tool 10 is retrieved at the surface, the

' valve head s2, seal ring ies, liner 74 and test ports 11o may conveniently be inspected and interior parts of the tool washed by breaking the threaded connections between housing sections 23, 24 and 25 and between the mandrel sections 30, 31 and 32. Such disassembly of the tool leaves the O-ring retainer 53 in place and the hydraulic delaying mechanism undisturbed. The liner 74 may be Unthreaded from the housing section 23, if desired, and if the valve seat 84 or the bore 100 of the liner have suffered any damage by erosion or the like, such liner may conveniently be replaced at a minimum expense.

While the well tool 10 has been described in conjunction with the test of a formation 19 at the bottom of an uncased borehole, it will be evident that the well tool may be used for other types of testing such as the testing of selected formations at an intermediate depth in the hole, formation testing and water shut-off tests in cased holes, the placing of wells on production for extended periods of time, and acidizing of formations in open hole. Further, the well tool 10 illustrated in FIGS. 1-4 is subject to various modifications including, for example, the modications shown in FIGS. A and 5B.

Referring now to FIGS. 5A and 5B, there is shown a moditied well tool a comprising a multi-section tubular housing 25a including sections 21a, 22, 23a, 24 and 25 and telescopically received therein, a tubular mandrel 26a including sections 27a, 28, 29, 3i), 31 and 32. These housing and mandrel sections correspond generally with the housing and mandrel sections of similar numerical designations shown in FIGS. 1-4 and are similarly assembled with endwise Huid-tight threaded connections. The upper end of the upper mandrel section 27a has a fluid-tight threaded connection with a top sub 34a which, in turn, provides a thread box for making a threaded connection with pipe string 14 or the like, while the lower end of bottom housing section 25 is adapted for threaded connection with packer 15.

The mandrel section 27a has an enlarged lower end portion 125 received in the bore of housing section 21a for supporting engagement with reduced upper end portion 126 of the housing section 21a in the extended position of the mandrel with respect to the housing, while upper face of portion 126 supports the top sub 34a in the retracted position of the mandrel. To prevent co-rotation between the mandrel and housing, a longitudinal spline connection 129 may be provided between housing section 21a and mandrel section 27a.

Within the housing section 22 is an hydraulic delaying mechanism which serves the purpose of retarding downward stroking of the mandrel relative to the housing while permitting a rapid upstroke. To provide such mechanism, there is dei-ined between the housing section 22 and the mandrel the annular oil chamber 52 sealed at its upper and lower ends by O-ring retainers 13() and 53, respectively. The retainer 130 has interior grooves receiving O-rings 131 to provide a sliding seal with respect to mandrel section 28. By making the outer diameter of mandrel sections 28 and 30 the same, the volume of oil chamber 52 remains constant with stroking of the mandrel. Threaded plugs 133 provide closures for access ports at the upper and lower ends of chamber 52 through which a suitable incompressible fluid, such as a high temperature, high pressure oil, may be introduced.

To retard the movement of the mandrel downwardly through the oil chamber '52, mandrel section 29 slidably carries a sleeve valve 135 having an upper annular fiat end surface 136 for sealing with a flat annular valve seat 137 as a downwardly directed shoulder on the mandrel lsection 29. A coil spring 139 may encircle the mandrel section 29 and be supported by a washer 140 retained at the junction of sections 29 and 30 to act upwardly upon the sleeve valve 135, maintaining it sealed with the valve seat 137 despite the downward force of gravity. Defined between the mandrel section 29 and the surrounding sleeve valve 135 is a longitudinal passage 142 extending interiorly through the sleeve Valve. During the downstroke, this interior passage 142 is closed by the sealed engagement between the sleeve 1@ valve and the seat 137 so that the transfer of fluid in the chamber 52 from the lower side to the upper side of the sleeve valve is accommodated only by a restricted annular passage 143 defined between the exterior surface of sleeve valve 135 and the bore of housing section 22. This passage 143 may, for example, have a radial dimension on the order of a few thousandths of an inch. During upstroke of the mandrel, of course, the sleeve valve 135 leaves the valve seat 137 to permit flow through the interior passage 142.

Referring particularly to FIG. 5B now, the intermediate housing lsection 23a is seen to have an interior threaded connection at its lower end vwith a valve collar 145. In

f similarity to the liner 74 of FIG. 2, the collar 145 has an enlarged portion 76 seated on the lower end of housing section 23a and extending downwardly to provide the valve seat 84 for sealing with valve head S2. A liner 147 separate from the valve collar 145 is secured within the ybore of housing section 23a by reception of an enlarged upper end portion 148 of the liner in an upwardly opening counter bore 149 provided at the upper end of housing section 23a. As may be seen, the O-ring retainer 53 prevents upward displacement of liner 147 while O-rings 81 and 15@ received in external annular recesses at the upper and lower ends of liner 147 seal the exterior of the liner with respect to the bore of housing section 23a.

As a further modication with respect to the embodiment shown in FIGS. 1-4, the seal ring 103 is seen in FIG. 5B t-o carry O-rings 152 in spaced annular grooves formed in the exterior of the lseal ring, in lieu of the sealing element 106. While O-rings carried externally of a mandrel below the test ports are usually subject to a washing out of their grooves by inrushing iluid, it will be appreciated lthat the O-rings 152 are safely lodged within counter bore 89 of valve head 82 prior to opening of the valve head whereby the O-rings 152 may be retained for successive operations.

In other respects the modiiied well tool 15a of FIGS. 5A and 5B may be similar to the well tool 10 described in conjunction with FIGS. 1-4 and its operation will be understood from that described in conjunction with the Well tool 1t) except that provision is not made for obtaining a shut-in pressure test by operation of the well tool 10a itself.

In a further embodiment illustrated in FIGS. 6, 7 and 8, the sliding seal afforded by the seal ring 103 is replaced by a poppet-type annular valve and, similarly, a poppettype annular valve may be substituted for the sliding seal valve which controls the equalizing ports.

More particularly, there is shown in FIG. 6 the valve portion of a modified well tool 19h, which may be substituted either for the valve portion of well tool 10 shown in FIG. 2 or for the valve portion of well tool 10a shown in FIG. 5B. The housing 2tb of the modified valve portion is again made up: of threadedly connected sections, namely, sections 22, 23b, 24b and 25. Likewise, the modified mandrel 2Gb is made up of threadedly connected sections 30, 31, 32b and a new lower section 33. As before, the mandrel is slidably ybut nonrotatively received in the housing for limited longitudinal movement between extended and retracted positions and, if desired, an intermediate, shut-in pressure position.

The principal valve controlling the longitudinal ow passage 70 is of the poppet-type similar to valve '7G-82 of FIG. 5B and comprises a modied valve head 82h slidably received on the mandrel section 3217. The moditication of valve head g2b resides in elimination of the counter bore 39, rendered unnecessary by elimination of the O-rings 152 from the modified valve ring or head 103i).

A secondary valve controlling longitudinal ow through the fluid passage 71.# is provided by the valve head 103]; in cooperation with liner section 155 and particularly its downwardly and outwardly tapered surface providing a valve seat 156. In the closed position shown in FIG. 6

valve seat 156 engages valve surface 115 of the annular head 103i: with a complementary taper. 4Liner section 155 may be retained at its upper end and sealed with respect to the housing in the same manner as liner section 147 of FIG. 5 b but is of shorter length, supported in spaced relationship within an enlarged upper bore portion 158 of housing section 2317. 'Ihe bore of liner section 155 is sized to receive the mandrel sections 30 and 31 in closely iitted, sliding relation, the valve seat 156 carried by the liner section being spaced only a short distance below the downwardly facing shoulder 104 of mandrel section 31 in the extended position of the mandrel.

In order that the valve head 103b may remain in its closed -upper position until the mandrel has been stroked a predetermined short distance downwardly, the upper yface of the valve head is spaced this short distance below the shoulder 104 of mandrel section 31, thereby to rem-ain on the valve seat 156 until travel of the mandrel section 31 through the valve head brings the shoulder 104 into engagement ywith the upper face of the valve ring. Conveniently, a bias spring 159 may encircle the reduced diameter portion of the mandrel section 31 so as to act in compression between the upper face 185 of mandrel section 32b and the lower face 113 of valve ring 103b. The spring is thus eective to hold the valve ring 103b on the valve seat 156 until downward stroking of the mandrel overcomes the spring bias and any hydrostatic pressure acting upwardly upon the valve ring. With further downward stroking of the mandrel, the valve ring 103b travels with spaced clearance through the reduced bore portion 160 of the housing section 23b and similarly through the bore of collar 146 into engagement with the upper face 161 of the valve head 82]). The surfaces 113 and 161 are then in engagement, as seen in FIG. 8, whereby the test ports 110 may be opened to longitudinal flow through passage 70.

While the arrangement of equalizing ports shown in FIG. 2 may be employed in the modified well tool 10b, the poppet-type equalizing valve shown in FIG. 6 may instead be used with this type of valve. Equalizing ports 162 are preferably inclined upwardly and outwardly at an angle of say 45 degrees through the wall of housing section 24b, oifset from longitudinal bypass passages 90. To provide for closure of the equalizing ports 162, the housing section 24b receives in its lower end a liner section 163 threadedly connected at 164 and sealed by O-ring 165. The liner section 163 extends in downwardly and inwardly spaced relation from the enlarged bore of housing section 25 to leave an annular passage in communication with bypass passages 9i) and at its upper end the liner section 163 provides avalve seat 163a. An external flange 166 of the liner section 163 engages the lower end of housing section 24b to position the valve seat 163a immediately below the inner end of equalizing ports 162, the upper end of liner section 163 having a counter bore 167 below valve seat 163er to accommodate unrestricted ow of fluid through the ports 162.

A valve head 168 is slidably carried by the mandrel section 32b at its lower end for cooperation with the valve seat 163a to provide a poppet-type valve for controlling the equalizing ports. Thus, the valve head 168 is provided with a valve surface 169 on its enlarged lower end, having an upward and outward taper conforming with the complementary taper of the valve seat 163:1 and preferably corresponding with the inclination of the ports 162. To bias the valve head 168 toward its closed position in a manner similar to the biasing of valve head 82h, the same coil spring 94 may be employed. As seen in IFIG. 7, for example, the coil spring 94 acts in compression between the lower yface 96 of valve head 82h and upper face 170 of valve head 168 when both the valve heads are in their closed position, and the spring contracts when either valve head is in its open position. To overcome the bias of spring 94 in the open position of valve head 168 and to provide for opening of the valve head from its closed position upon upward stroking of the mandrel, lowermost mandrel section 33 has an external flange 172 which extends outwardly beyond the -proiile of mandrel section 3219 to engage lower face 173 of valve head 168 after a predetermined upward travel from the lowermost position of the mandrel (FIG. 8 to FIG. 7). To prevent leakage around the valve head 168 when it is in its closed position, and also in its open position, O-ring carried in an external groove of the valve head seals with the reduced bore of housing section 24b and O-ring 176 carried in an internal groove of the valve head seals with the outer periphery of mandrel section 32h.

In a typical operation of the modified well tool 10b of FIGS. 6, 7 and 8, the tool is lowered into a well with both the main valve 82b-84 and the secondary valve 103b-156 closed to the longitudinal ow of fluid through passage 70, as seen in FIG. 6. With setting of the packer by weight exerted through the test string, the mandrel 26b is stroked downwardly at a rate controlled by the hydraulic delaying mechanism. After, say, a quarter inch of downward travel, the valve head 10317 of the secondary valve is moved of valve seat 156. Thereafter, the Valve head 103k moves downwardly with a mandrel.

Upon a further downward travel of, say, three-quarters of an inch, the valve head 168 for the equalizing valve is carried =by the bias of spring 94 into closing engagement with the valve seat 163a. Thereupon, further flow of well iiuid through the equalizing ports 162 is cut off and the valve head 168 remains stationary with respect to the housing. Yet a further downward stroking of the mandrel for a distance, say, of 51/2 inches brings the lower shoulder 113 of secondary valve head 103i) into engagement with the upper face 161 of main valve head 82b to lift the main valve head 82h off valve seat 84. As in the previously described embodiments, this opening of the main valve during the hydraulically retarded downward stroking of the mandrel creates a shock force with overcoming of the hydrostatic pressure of the valve head such that an operator at the surface may derive a tangible or audible indication of the opening of the testing tool for flow of formation fluid into the test string thereabove.

lf desired, the mandrel may be returned from the open position illustrated in FIG. 8 to an intermediate position shown in FIG. 7 Iby an actuating mechanism such as that shown in FIG. l. In this case, the main valve head B2b engages valve seat 84 again to close ot the longitudinal ow passage 70, while the equalizing valve remains closed so that pressure may be built up below the testing tool. With further upward stroking of the mandrel, the equalizing valve head 168 iirst moves to its open position and then the secondary valve head 10311 moves to its closed position, thus assuring retention of the recovered sample o-f formation fluids in the test string above the testing tool. Since the secondary valve closes after the primary valve has already closed, its sealing its reliably accomplished without risk of fluid cutting or erosion.

It will be evident that the foregoing embodiments of the invention are subject to various changes and modification including, for example, use of the last described equalizing valve in lieu of equalizing Valves shown in FIG. 2 or FIG. 5b. Also, the hydraulic delaying mechanism may 'be positioned at the lower end of the tool and other equalizing valve arrangements may be devised in lieu of those herein described. If desired the mandrel section 32 may be blanked off, in lieu of the emergency circulating valve 98, particularly in the embodiment of FIG. 6 where primary and secondary valves 821; and 103b will accommodate ilow of fluid downwardly under pump pressure applied at the surface.

f The valve ring 103b of FIG. 6 may, if desired, have a sealing element like ring 103 arranged to provide a similar sliding seal which is protectively received in a i3 counter bore (not shown) of valve head 82b. In addition to, or in lieu of the hydraulic delaying mechanism, the testing tool may be maintained in its closed position by a heavy bias spring acting with respect to the mandrel and housing.

Accordingly, the invention is not to be limited to the embodiments illustrated and described but is of a scope defined in the appended claims.

We claim:

l. A well tool comprising a tubular housing having an annular valve seat along its bore, an annular valve head in said bore movable between a closed and an open position with respect to said valve seat, means normally biasing said valve head toward its closed position, a tubular mandrel extending into said bore and slidably through said valve head for limited longitudinal movement with respect to said housing, said mandrel having a lateral flow port spaced therealong for movement past said valve seat which port is opened by movement of said valve head to its open position to place the interior of said mandrel on one side of said valve head in communication with the exterior of said mandrel on the other side of said valve head, and a member carried by said mandrel and projecting outwardly therefrom for engaging said valve head to move it with said mandrel, said member being spaced from said valve head prior to engagement and arranged for moving said valve head with said mandrel to its open position as said iiow port is moved past said valve seat.

2. A well tool comprising a tubular housing having an annular valve seat along its bore, an annular valve head in said bore movable between a closed and an open position with respect to said valve seat, means normally biasing said valve head toward its closed position, a tubular mandrel extending into said bore and slidably through said valve head, means for limiting longitudinal movement of said mandrel with respect to said housing, means providing a sliding seal between said mandrel and said valve head in at least the closed position of said valve head, said mandrel and said housing together defining a ow channel exterior to said valve head and lengthwise through said tool which is opened and closed by said Valve head and valve seat, annular means arranged between said mandrel and said housing to provide a seal therebetween and along said flow channel only when it is closed by said valve head and valve seat, and means carried by said mandrel for moving said valve head after a predetermined displacement of said mandrel relative to said valve head to control iiow through said channel.

3. A well tool comprising a tubular housing having an annular valve seat along its bore, an annular valve head in said bore movable between a closed and an open position with respect to said valve seat, said valve head and said valve seat having confronting surfaces which are in abutting engagement in the closed position of said valve head, means normally biasing said valve head toward its closed position, a tubular mandrel extending into said bore slidably through Said Valve head and having a lateral iiow port communicating through said mandrel with only one end thereof, means for limiting longitudinal movement of said mandrel with respect to said housing, said mandrel and said housing together defining a fiow channel through said tool which extends through said port and is opened and closed by said valve head and valve seat in their opened and closed position respectively, and means carried by said mandrel for moving said valve head to its open position when said mandrel is displaced to position said port opposite the opening between said valve head and valve seat, thereby permitting flow through said channel.

4. A well tool comprising a tubular housing having an annular valve seat along its bore, an annular valve head in said bore movable between a closed and an open position with respect to said valve seat, a tubular mandrel extending into said bore slidably through said valve head 'i4 and having a lateral iiow port spaced longitudinally of said valve head, means for limiting longitudinal movement of said mandrel with respect to said housing, said mandrel and said housing together defining a iiow channel through said tool which extends through said port and is opened and closed by said valve head and valve seat, means acting between said valve head and said housing for biasing said valve head toward its closed position, and means carried by said mandrel for moving said valve head to its open position when said port is displaced opposite the opening between said valve head and valve seat to permit iiow through said channel.

5. A well tool comprising a tubular housing having a reduced bore section and an enlarged bore section and an annular valve seat therebetween, an annular valve head in said enlarged bore section movable between a closed and an open position with respect to said valve seat, means normally biasing said valve head toward its closed position, a tubular mandrel extending slidably into said bore sections through said valve head, means retaining said mandrel in said bore sections for limited longitudinal movement with respect to said housing, said mandrel having a lateral tiow port, means providing a sliding seal between said mandrel and said reduced bore section cooperating with said valve head to close `said port only when said valve head is in its closed position with respect to said valve seat, and means carried by said mandrel for moving said valve head to its open position after a predetermined displacement of Said port from said reduced bore section to a position adjacent said valve seat.

6. A well tool comprising a tubular housing having an annular valve seat along its bore, an annular valve head in said bore movable between a closed and an open position with respect to said valve seat, means normally biasing said valve head toward its closed position, a mandrel extending into said bore and through said valve head for limited longitudinal movement with respect to said housing, means adapted to provide a fluid 'tight connection between said mandrel and a string of pipe, said mandrel and said housing together defining a fiow channel through said tool for communication with the interior of said pipe, which channel is opened and closed by movement of said valve head, means providing a sliding annular seal along said channel between said mandrel and said housing bore only for a predetermined displacement of said mandrel while said valve head is in its closed position, and means carried by said mandrel for moving said valve head to its open position after said predetermined displacement of said mandrel relative to said housing and said valve head to open said channel of fluid tiow.

7. A well tool comprising a tubular housing having an annular valve seat along its bore, an annular valve head in said bore movable between a closed and an open position with respect to said valve seat, means normally biasing said valve head toward its closed position, a mandrel extending slidably into said bore and through said valve head for limited longitudinal movement with respect to said housing, said mandrel and said housing together defining a flow channel through said tool which is opened and closed by movement of said valve head, means providing a sliding annular seal between said mandrel and said housing bore only in the closed position of said valve head to seal oli said channel, and means carried by said mandrel for moving said valve head to its open position after a predetermined displacement of said mandrel relative to said valve head to open said channel to liuid liow therethrough, said valve head being arranged to protect said seal means from erosion by said fiuid iiow in its open position.

8. A well tool comprising a tubular housing including an exterior section defining an enlarged bore and a liner section removably secured within said exterior section adjacent said enlarged bore, said liner section having a uniform bore of reduced diameter terminating in a shoulder shaped to define a valve seat confronting said enlarged bore, a tubular mandrel received in said housing for limited movement between an extended and a retracted position, a seal ring carried by said mandrel providing an annular seal with said liner bore in the extended position of said mandrel, an annular valve head slidably carried on said mandrel in sealed relation thereto for movement within said enlarged bore between a closed and an open position with respect to said valve seat and normally biased toward its closed position, said valve head being engageable by said seal ring as said mandrel is moved toward its retracted position for displacement to said open position, said seal ring being displaced from said reduced bore into said enlarged bore as said mandrel is moved toward its retracted position, and means normally biasing said valve head toward its closed position.

9. A well tool comprising a tubular housing having a lirst bore section and a second bore section of larger diameter subjacent thereto and in communication with the lower end of said well tool, and a downwardly-facing annular valve seat at the junction of said sections, an annular valve head received in said enlarged bore section for movement between an open and a closed position with respect to said valve seat and having a conical valve surface confronting said valve seat for sealing engagement therewith in the closed position of said valve head, a tubular mandrel extending through said rst bore section and into said second bore section and arranged at its upper end Afor uid tight connection -with a string of pipe to continue the fiow course therethrough, said valve head being slidably fitted about said mandrel in sealed relation thereto and inwardly spaced from said second bore section to permit longitudinal fluid iiow therepast, means for biasing said valve head toward its closed position, said mandrel having an enlarged portion and an annular seal means carried thereby for providing a sliding seal with said first bore section only in the closed position of said valve head, said enlarged mandrel portion being engageable with said valve head upon downward movement of said mandrel to displace said valve head to its open position, said valve head having a counter bore opening upwardly to receive said enlarged portion and said seal means while in its closed position and extending upwardly about said seal means in its open position, said mandrel having a port opening above said seal means and in communication with the upper end of said mandrel which port is open through -said second bore section to the lower end of said Well tool Iwhen said mandrel is moved downwardly to displace said valve head from its closed position, means providing an annular seal between said mandrel and said housing above said port, means for blocking fluid iiow upwardly through said mandrel to said port and means for retarding downward movement of said mandrel relative to said housing prior to opening of said Valve head, said valve head having its lower face exposed for application of hydrostatic well pressure whereby overcoming said hydrostatic pressure upon opening said valve head transmits a shock upwardly through said well tool.

l0. A well tool comprising a tubular housing having at least two annular valve seats spaced along its bore, for each of said valve seats an annular valve head in said bore movable between a closed and an open position with respect to such valve seat, a mandrel extending into said bore and through said Valve heads, means resiliently biasing said valve heads toward their closed position, means for limiting longitudinal movement of said mandrel with respect to said housing between an extended and a retracted position, said mandrel and said housing tgether defining a ilow channel lengthwise through said tool which is closed when one of said valve heads is in its closed position, and means carried by said mandrel for moving one of said valve heads to its open position after a predetermined displacement of said mandrel relative to said housing and for moving another of said valve heads to its open position after a further such displacement of said mandrel to permit flow through said channel.

iii

ll. A well tool comprising a tubular housing having at least two annular valve seats of different diameter along its bore, for each of said valve seats an annular valve head in said bore movable between a closed and an open position with respect to such valve seat, a mandrel extending into said bore and through said valve heads for limited longitudinal movement with respect to said housing, means resiliently biasing said valve heads toward their closed position, said mandrel and said housing together defining a ow channel lengthwise through said tool which is closed when one of said valve heads is in its closed position, and means carried by said mandrel for moving one of said valve heads to its open position after a predetermined displacement of said mandrel relative to said housing and for moving another of said valve heads to its open position after a further such displacement of said mandrel to permit flow through said channel.

l2, A well tool comprising a tubular housing having two annular valve seats of different `diameter along its bore, for each of lsaid valve seats an annular valve head in said bore movable between a closed and an open position with respect to such valve seat, a mandrel extending into said bore and through said valve heads for limited longitudinal movement with respect to said housing, means resiliently biasing said valve heads toward their closed position, means providing a sliding seal between said mandrel and said valve heads, said mandrel and said housing together deining a iiow channel lengthwise through said tool which is closed by said valve heads when said mandrel is in its extended position, the valve head corresponding to said smaller diameter valve seat being sized to pass through the larger diameter valve seat, and means carried by said mandrel for moving the smaller diameter valve head to its open position after a predetermined displacement of said mandrel relative to said housing and for moving said smaller diameter valve head through the larger diameter valve seat and thereupon moving the larger diameter valve head to its open position by a further displacement of said mandrel to permit flow through said channel.

13. A well tool comprising a tubular housing having two annular valve seats of dierent `diai'neter along its bore, a -large diameter annular valve head for the iarge diameter valve seat yand a small diameter annular valve head for the small dia-meter valve seat, a tubular mandrel extending into said bore and through said valve heads and -interengaged with :said housing for limited longitudinal movement between an extended and a retracted position, said valve heads -being slidable along said mandrel in sealed relation thereto and movable between a closed and an open position with respect to the corresponding valve seat, said mandrel and said housing .together defining a iiow ychannel :lengthwise through said tool which is closed by said valve heads when said mandrel is in its extended position, means resiliently biasing said valve heads toward their closed position, and means carried Iby said mandrel for moving said smaller diameter valve head to its open position after a predetermined displacement of said mandrel Irelative .to said housing Itoward its retracted position, said smaller diameter valve head lbeing sized to pass through the larger Idiameter valve seat for engaging with and mov-ing said larger diameter valve head to its open position upon a further such displacement of said mandrel to permit flow through said channel.

14. A well tool comprising a tubular housing having smaller and larger diameter valve seats spaced along its bore, for each of said valve seats an annular valve head of corresponding diameter in said ybore movable between a closed and an open position with respect to -said valve seat, a tubular mandrel extending into said bore slidably through said valve heads -and having a lateral flow port spaced outwardly of said valve heads, means Ifor limiting longitudinal movement of said mandrel with respect to said Ihousing between an extended and a retracted position, ysaid mandrel and said housing together deining a ow channel through said tool which extends outwardly past said valve heads through ysaid port and outwardly through said mandrel, said ow -channel being closed by said valve heads when said mandrel is in its extended position, means for -biasing each of said valve heads toward its closed position, said mandrel having a smaller diameter portion terminating in an outer shoulder and spaced inwardly of said port slidable in sealed relation through said smaller diameter valve head for a predetermined displacement of said mandrel from its extended position, said smaller diameter valve head being engageable by said shoulder ifor movement with said mandrel after said predetermined displacement for passing through the larger diameter valve seat upon a further displacement to engage -said ylarge diameter valve head and move the same to its open position as said mandrel moves to its retracted position, and means -for retarding movement of said mandrel from its extended to its retracted position.

15. A well tool comprising a tubular housing having at rleast two annu-lar valve seats along its bore, for each of said valve seats an `annular valve head in said bore movabile :between a closed and an open position with respect to said valve seat, a tubular mandrel extending into said bore slidably through said valve heads and having a lateral flow port spaced longitudinally of one of said v-alve heads, means 'for limiting longitudinal movement of said mandrel with respect .to ysaid housing, said mandrel and said housing together dening a ilow channel through said tool which extends through said port and is opened and closed by said one valve head and the corresponding valve seat, said housing having a llateral port intermediate said two valve seats for fluid communication with one end of said well tool controlled by -another of said valve heads and the corresponding va-lve seat, means acting between said one and another valve heads 'for biasing the same toward their closed positions, and means canried by said mandrel for moving `said another valve head to -its closed position upon a predetermined displacement of said mandrel relative to said housing and for moving said one valve head to its open position upon the further such displacement of -said mandrel whereby said housing port is rst closed and then ysaid mandrel port is -opened to uid flow as said mandrel is displaced in one direction.

References Cited in the le of this patent UNITED STATES PATENTS 1,790,424 Johnston Ian. 27, 1931 2,073,107 Johnston Mar. 9, 1937 2,703,696 Deters `et al. Mar. 8, 1955 2,737,246 Moosman Mar. 6, 1956 2,799,346 Baker et al July 16, 1957 2,901,001 Nutter Aug. 25, 1959 

